package com.nateshao.play_with_data_structures.lesson_03_linked_list.linked_list_basics;

/**
 * @date Created by 邵桐杰 on 2021/11/4 22:38
 * @微信公众号 千羽的编程时光
 * @个人网站 www.nateshao.cn
 * @博客 https://nateshao.gitee.io
 * @GitHub https://github.com/nateshao
 * @Gitee https://gitee.com/nateshao
 * Description:
 */
public class LinkedList<E> {

    private class Node {
        public E e;
        public Node next;

        public Node(E e, Node next) {
            this.e = e;
            this.next = next;

        }

        public Node(E e) {
            this(e, null);
        }

        public Node() {
            this(null, null);
        }

        @Override
        public String toString() {
            return e.toString();
        }


    }

    private Node head;
    private int size;

    public LinkedList() {
        head = null;
        size = 0;
    }

    // 获取链表中的元素个数
    public int getSize() {
        return size;
    }

    // 返回链表是否为空
    public boolean isEmpty() {
        return size == 0;
    }

    // 在链表头添加新的元素e
    public void addFirst(E e) {
//        Node node = new Node(e);
//        node.next = head;
//        head = node;

        head = new Node(e, head);
        size++;
    }

    // 在链表的index(0-based)位置添加新的元素e
    // 在链表中不是一个常用的操作，练习用：）
    public void add(int index, E e) {

        if (index < 0 || index > size)
            throw new IllegalArgumentException("Add failed. Illegal index.");

        if (index == 0)
            addFirst(e);
        else {
            Node prev = head;
            for (int i = 0; i < index - 1; i++)
                prev = prev.next;

//            Node node = new Node(e);
//            node.next = prev.next;
//            prev.next = node;

            prev.next = new Node(e, prev.next);
            size++;
        }
    }

    // 在链表末尾添加新的元素e
    public void addLast(E e) {
        add(size, e);
    }

}
